This invention relates generally to the field of surface acoustic wave (SAW) signal processing, and more particularly to a technique and apparatus for the frequency partitioning of a surface acoustic wave having a wideband RF spectrum into a multiplicity of discrete narrowband contiguous output signals. The invention is especially useful and effecacious in use with wideband early warning (EW) threat signal receivers comprised in electronic countermeasure (ECM) systems in electronic warfare, since with the present invention, any incoming threat signal can be detected, isolated, and characterized as to source.
In accordance with surface acoustic wave (SAW) technology, a mechanical ripple, or wave, travels along the surface of a substrate in much the same manner as an ocean wave travels along a body of water. These surfaces waves are both generated and detected by transducer elements which convert energy back and forth between the electrical and the mechanical domains. The base or substrate material is a piezoelectric material which acts in the normal and well known way of producing electrical voltages in response to mechanical pressures applied to crystals of the material comprising such substrate.
Radio frequency (RF) acoustic surface wave devices have certain very unique advantages over conventional electromagnetic and electronic devices. Surface acoustic wave devices, for example, may be used to effect desired time delays in signal transmission for whatever purpose may be desired. At any given frequency, an acoustic wavelength is significantly smaller than an equivalent electromagnetic wavelength by a factor in the order of 100,000. This permits the signal processing of SAW signals in devices of extremely small physical size.
It is a principle object of the present invention to provide a frequency partitioning system which is particularly useful in the detection and categorizing of a specific threat signal of interest in early warning detection in the area of electronic warfare.
A further and important object of this invention is to provide a frequency partitioning channellizing system which can be embodied in microcircuit equipment with consistently good reproducibility of the system hardware, consistently reliable results, and the ruggedness and simplicity which lends itself to utilization in military applications.
In general, the present invention comprehends apparatus for frequency partitioning and channellizing a wideband RF spectrum surface acoustic wave signal into a multiplicity of narrowband contiguous output signals and comprises, in combination, a surface wave conductive base or substrate; an input transducer on said base disposed aslant the direction of reception signal propagation; a first multiplicity of output transducers on said base arranged in spaced-apart relationship along a first longitudinally extending side of said input transducer but apart therefrom; and a second multiplicity of output transducers on said base arranged in spaced relationship along a second longitudinally extending side of said input transducer and spaced therefrom, one each of said second multiplicity of output transducers disposed opposite a space between the output transducers in said first multiplicity of output transducers.